[PATCH rdma-next v3] RDMA/mana_ib: Clamp adapter capabilities at the ib_device_attr boundary

[Erni Sri Satya Vennela <ernis@linux.microsoft.com>]

mana_ib stores its adapter capabilities internally as u32 in
struct mana_ib_adapter_caps. The IB core, however, exposes the
corresponding device attributes through struct ib_device_attr, where
fields such as max_qp, max_qp_wr, max_send_sge, max_recv_sge,
max_sge_rd, max_cq, max_cqe, max_mr, max_pd, max_qp_rd_atom,
max_res_rd_atom and max_qp_init_rd_atom are signed int.

mana_ib_query_device() is the only place that copies the cached u32
caps into these int fields. If a cap exceeds INT_MAX, the implicit
u32-to-int narrowing yields a negative value. Clamp each cap to
INT_MAX at this boundary so the values handed to the IB core are always
non-negative.

While here, fix a related overflow in the computation of
max_res_rd_atom. It is derived as max_qp_rd_atom * max_qp, both of
which are int after the assignment above; the multiplication can
overflow an int even with the new clamps in place. Widen to s64
before multiplying and clamp the result to INT_MAX.

Signed-off-by: Erni Sri Satya Vennela <ernis@linux.microsoft.com>
---
Changes in v3:
* Drop clamping from mana_ib_gd_query_adapter_caps(). The internal u32
  caps cache does not need to be clamped.
* Move all clamping exclusively to mana_ib_query_device(), which is the
  only place the cached u32 values are narrowed into the signed int
  fields of struct ib_device_attr.
* Reframe commit message: this is a u32-to-int type boundary fix, not a
  CVM/untrusted-hardware hardening patch.
Changes in v2:
* Update patch title.
---
 drivers/infiniband/hw/mana/main.c | 33 ++++++++++++++++++++-----------
 1 file changed, 21 insertions(+), 12 deletions(-)

diff --git a/drivers/infiniband/hw/mana/main.c b/drivers/infiniband/hw/mana/main.c
index ac5e75dd3494..ca843083140f 100644
--- a/drivers/infiniband/hw/mana/main.c
+++ b/drivers/infiniband/hw/mana/main.c
@@ -555,19 +555,28 @@ int mana_ib_query_device(struct ib_device *ibdev, struct ib_device_attr *props,
 	props->vendor_part_id = dev->gdma_dev->dev_id.type;
 	props->max_mr_size = MANA_IB_MAX_MR_SIZE;
 	props->page_size_cap = dev->adapter_caps.page_size_cap;
-	props->max_qp = dev->adapter_caps.max_qp_count;
-	props->max_qp_wr = dev->adapter_caps.max_qp_wr;
+	/*
+	 * mana_ib stores adapter capabilities internally as u32, but the
+	 * corresponding ib_device_attr fields are signed int. Clamp each
+	 * value at this boundary so a cap larger than INT_MAX is never
+	 * narrowed into a negative value visible to the IB core or
+	 * userspace.
+	 */
+	props->max_qp = min_t(u32, dev->adapter_caps.max_qp_count, INT_MAX);
+	props->max_qp_wr = min_t(u32, dev->adapter_caps.max_qp_wr, INT_MAX);
 	props->device_cap_flags = IB_DEVICE_RC_RNR_NAK_GEN;
-	props->max_send_sge = dev->adapter_caps.max_send_sge_count;
-	props->max_recv_sge = dev->adapter_caps.max_recv_sge_count;
-	props->max_sge_rd = dev->adapter_caps.max_recv_sge_count;
-	props->max_cq = dev->adapter_caps.max_cq_count;
-	props->max_cqe = dev->adapter_caps.max_qp_wr;
-	props->max_mr = dev->adapter_caps.max_mr_count;
-	props->max_pd = dev->adapter_caps.max_pd_count;
-	props->max_qp_rd_atom = dev->adapter_caps.max_inbound_read_limit;
-	props->max_res_rd_atom = props->max_qp_rd_atom * props->max_qp;
-	props->max_qp_init_rd_atom = dev->adapter_caps.max_outbound_read_limit;
+	props->max_send_sge = min_t(u32, dev->adapter_caps.max_send_sge_count, INT_MAX);
+	props->max_recv_sge = min_t(u32, dev->adapter_caps.max_recv_sge_count, INT_MAX);
+	props->max_sge_rd = min_t(u32, dev->adapter_caps.max_recv_sge_count, INT_MAX);
+	props->max_cq = min_t(u32, dev->adapter_caps.max_cq_count, INT_MAX);
+	props->max_cqe = min_t(u32, dev->adapter_caps.max_qp_wr, INT_MAX);
+	props->max_mr = min_t(u32, dev->adapter_caps.max_mr_count, INT_MAX);
+	props->max_pd = min_t(u32, dev->adapter_caps.max_pd_count, INT_MAX);
+	props->max_qp_rd_atom = min_t(u32, dev->adapter_caps.max_inbound_read_limit, INT_MAX);
+	props->max_res_rd_atom = min_t(s64,
+				       (s64)props->max_qp_rd_atom * props->max_qp,
+				       INT_MAX);
+	props->max_qp_init_rd_atom = min_t(u32, dev->adapter_caps.max_outbound_read_limit, INT_MAX);
 	props->atomic_cap = IB_ATOMIC_NONE;
 	props->masked_atomic_cap = IB_ATOMIC_NONE;
 	props->max_ah = INT_MAX;
-- 
2.34.1